The present invention relates, in general, to apparatus for measuring and controlling the supply of electric energy at a use site and, more particularly, to such apparatus which also detect a tamper event involving the apparatus.
In the electric utility industry, watthour meters are typically employed to measure electric power used at a building or home site. A socket housing is mounted on a convenient wall of the residence or commercial building and contains pairs of line and load terminals which are respectively connected to the electric utility line conductors and the building load distribution conductors. The terminals typically receive blade contacts on a plug-in watthour meter to complete an electric circuit through the meter between the line and load terminals.
Plug-in socket adapters and socket adapters/extenders, both hereafter referred to simply as socket adapters, are designed to plug into the meter socket housing terminals. Such socket adapters are employed to convert a ringless style socket to a ring style socket or to extend the mounting position of the jaw terminals in the socket outward from the socket for mounting various electrical equipment, such as test devices or survey recorders, in the socket. The watthour meter is then plugged into jaw contacts carried within the socket adapter. The socket adapter jaw contacts are connected, either integrally or via separate electrical connections, to blade terminals extending rearwardly of the socket adapter housing for plug-in engagement with the socket terminals or jaw contacts.
Meter reading personnel periodically inspect each meter site and record utility meter readings, either visually or by using a probe to retrieve power usage data stored in solid state memory of the watthour meter.
To increase data collection efficiency and reliability, watthour meters are now available which include interface equipment designed to permit remote interrogation of the meter and transmission of electric power usage data. Utility meters located at each customer site are connected in data communication to a central billing facility via various communication methods, including power line signal transmission, dedicated signaling lines, use of the public telephone switching network, and radio frequency signal transmission.
Another factor which arises with any watthour meter design, whether of the automatic reading type or a more conventional, electronic or mechanical watthour meter, is the ability to detect tampering with the meter, such as the removal of the meter to insert wires to bypass the meter and thereby obtain free, unmetered power. In addition to removing the meter, certain tampering events involve the removal and the replacement of the meter in an inverted position in the socket so as to cause reversal of the rotation of the measuring disk.
As a result of increased usage of automatic meter reading installations, on-site inspection of the watthour meter mounting configuration by utility personnel has become less frequent. This has encouraged would be tamperers to increase their efforts to unauthorizedly obtain electric power from the meter socket without payment. This is despite the elaborate anti-tampering design features built into each watthour meter, meter socket adapter and meter socket and other tampering detection circuits and devices.
Older tamper detection devices were mechanical in nature and frequently included an orientation sensitive switch, also known as a tilt switch, which detected reverse mounting of the watthour meter in the socket after the meter is first removed from the socket. Once removed, a single phase meter could be installed upside down resulting in reverse rotation of the meter disc and register dials which record cumulative energy consumption. The existence of a single tampering event or the recording of the number of times a tampering event was typically detected and stored in a memory device in the watthour meter.
While effective, such mechanical tampering detection devices still require some type of on-site inspection to determine the tamper detection elements detected a tampering event. As noted above, such on-site inspections are typically at a decreased frequency such that tampering may go on undetected for a considerable length of time.
While the introduction and increasing use of automatic meter reading equipment lengthens the time between on-site inspections of meter installations, the direct communication capabilities of such automatic meter reading equipment can provide an immediate indication of an on going tampering event thereby allowing the utility to take immediate corrective action to stop the unauthorized use of electric power at a particular meter site.
Thus, it would be desirable to provide an electric energy measurement apparatus which overcomes the problems of previously electric energy measurement or meter reading apparatus with respect to detecting and communicating tampering events. It would be desirable to provide an electric energy measurement apparatus capable of utilizing communications through a global telecommunication network between the remote meter units and a central site. It would also be desirable to provide an electric energy measurement apparatus which is capable of detecting, reporting, and, optionally, taking action to report and/or disconnect electric power to a use site whenever a tamper event is detected.